Giant Hogweed (Heracleum mantegazzianum) is a very dangerous plant and can cause blindness if introduced to the eyes. Photo courtesy of WDNR.

Giant Hogweed is a very tall plant, reaching 15 feet or more and has leaf and flower characteristics similar to our native Cow Parsnip (Heracleum sphondylium) and Angelica (Angelica atropurpurea). But both of these native plants only reach four to eight feet tall and their leaves are one-fifth the size of Giant Hogweed. Also, while Cow Parsnip has a green stem and Angelica has a red stem, Giant Hogweed has dark purple spots on its stem. Be sure to check closely, but carefully before you touch.

All like moist, rich soil and can grow in sun to partial shade.

To read the complete information gathered by the Special Assessment Group before classifying Giant Hogweed as a prohibited invasive species, go to literature review.

To learn more about Wisconsin’s noxious weeds classifications see NR 40.